feat: Add AvailableMedians method

[rbajollari]

Description

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[codecov-commenter]

Codecov Report

Merging #1657 (01ff5e4) into main (d104b4e) will decrease coverage by 0.08%.
The diff coverage is 33.33%.

@@            Coverage Diff             @@
##             main    #1657      +/-   ##
==========================================
- Coverage   55.32%   55.24%   -0.09%     
==========================================
  Files          73       73              
  Lines        7515     7527      +12     
==========================================
  Hits         4158     4158              
- Misses       3035     3043       +8     
- Partials      322      326       +4     

Impacted Files	Coverage Δ
x/oracle/keeper/historic_price.go	66.45% <33.33%> (-5.58%)	⬇️

[toteki]

Nice.

On performance, is it much of a problem to be calling AvailableMedians and then (usually) MedianOfMedians right after?

[rbajollari]

Nice.

On performance, is it much of a problem to be calling AvailableMedians and then (usually) MedianOfMedians right after?

They're both going to call HistoricMedians() which iterates through medians in the store. The other option instead of having this method is to add an extra parameter to MedianOfHistoricMedians() like minMedians which would enforce a minimum amount of medians for it to return something by checking the length of the medians returned by HistoricMedians(). This would be one less call to HistoricMedians() than first calling AvailableMedians() and then MedianOfHistoricMedians(). What do you think about this approach @toteki?

[toteki]

I think that enforcement would create an error return, which would be indistinguishable from other more serious errors (invalid denom, etc) with inspecting the error.

What about keeping the AvailableMedians method but also adding a return to the other functions, for example MedianOfMedians(ctx,denom,numStamps) (sdk.Dec, uint32, error) where the uint32 is the number of stamps actually read?

Would reduce the load from 2 -> 1 HistoricMedians and allow leverage to determine whether a lower than expected number of stamps constitutes an error or just a case.

[rbajollari]

I think that enforcement would create an error return, which would be indistinguishable from other more serious errors (invalid denom, etc) with inspecting the error.

What about keeping the AvailableMedians method but also adding a return to the other functions, for example MedianOfMedians(ctx,denom,numStamps) (sdk.Dec, uint32, error) where the uint32 is the number of stamps actually read?

Would reduce the load from 2 -> 1 HistoricMedians and allow leverage to determine whether a lower than expected number of stamps constitutes an error or just a case.

Made that update to MedianOfMedians and the other methods as well i.e. AverageOfMedians, MaxOfMedians, and MinOfMedians👍

[robert-zaremba]

we should strictly avoid unnecessary operations in blockchain, which will consume extra gas. Here you only need to count elements, you don't even need to deserialize them, nor load them.

[toteki]

Change to treatment of zero case requested

[toteki]

Nice, everything's been addressed

[robert-zaremba]

lgtm